Project Summary Cardiovascular (CV) disease (CVD) continues to be the number one cause of death in the United States and worldwide. CVD risk factors are not only increasingly prevalent in children, but they track into adulthood and are associated with intermediate and hard outcomes. Therefore, to slow the current trajectory of adult CVD morbidity and mortality, efforts aimed at prevention starting in the pediatric age group are essential. Prior to the development of clinically evident CVD risk factors such as hypertension, individuals manifest subtle alterations to their vasculature. Arterial stiffness, endothelial dysfunction, and greater blood pressure variability are examples of subclinical changes that precede the development of more significant clinical disease and clinical outcomes. This study aims to determine the individual and combined effects of diet quality and sodium intake on pre-clinical CV measures, including measures of vascular function and blood pressure phenotype, in children. Further, using 24-hour ambulatory blood pressure monitoring we will identify children who are salt- sensitive and investigate for biomarkers that predict response to sodium reduction. To achieve these aims, this proposal will build on an ongoing controlled feeding study of pre-adolescents and adolescents. Camp DASH (U01HL128834) is a blinded 2x2 factorial cross-over feeding study designed to test the effects of diet [the Dietary Approaches to Stop Hypertension (DASH) diet vs. Usual diet] and sodium intake (high vs. low sodium) on seated blood pressure and plasma lipid levels among children 11-15 years of age. This proposal will be conducted as an ancillary to the Camp DASH trial. It will add measures of arterial stiffness and endothelial function (pulse wave velocity, augmentation index, ambulatory arterial stiffness index, and laser Doppler flow perfusion measures) and 24-hour ambulatory blood pressure monitoring to the parent study. Determining the impact of dietary interventions on subclinical CVD markers and identifying biomarkers that predict response to sodium restriction could significantly improve preventive and treatment efforts. More importantly, this knowledge could help shape public policy as focus shifts from treatment of CVD risk factors to prevention of CVD risk factor development. This study could therefore have far reaching public health implications, providing evidence for dietary change and sodium reduction in children.